REPEATED ANKLE SPRAINS

Every once in a while, my ankle gives out on me. I sprained it about two years ago, and it feels like I’m slightly respraining it each time this happens. Why does this keep occurring?

What you’re describing sounds like a condition called functional instability (FI). This happens when someone can walk on their foot, but the ankle occasionally gives way without warning. It’s one of the most common long-term complications after an ankle sprain.

The exact cause of FI isn’t entirely clear. The simplest explanation is that the ligaments damaged during the initial injury aren’t adequately supporting the ankle. However, if that were the only issue, your ankle would be unstable with every step, which isn’t the case.

There are a couple of theories that may explain FI. One is known as articular deafferentation. This theory suggests that tiny sensors, called mechanoreceptors, located in the joint capsule and surrounding ligaments, are damaged during the initial injury. These mechanoreceptors play a crucial role in ankle stability by signaling muscles to react and prevent the ankle from moving too far in any direction. When these receptors are damaged, the muscles may not respond quickly enough, causing the ankle to give out.

Another theory is the feed-forward motor control theory. This concept suggests that the body learns to react to certain movements or positions based on past experiences. For example, when you prepare to take a step, the muscles around the ankle contract to position it correctly and stabilize it. After an injury, the muscles might contract too early in anticipation of protecting the joint, but this abnormal muscle control can lead to the ankle giving way.

Fortunately, this problem can sometimes be addressed with a tailored exercise program designed to improve neuromuscular control. A physiotherapist can guide you through specific exercises to help restore normal function and stabilize your ankle.

Reference: Eamonn Delahunt, BSc, et al. “Altered Neuromuscular Control and Ankle Joint Kinematics During Walking in Subjects with Functional Instability of the Ankle Joint.” The American Journal of Sports Medicine, December 2006, Vol. 34, No. 12, pp. 1970-1976.